The ligating versatility of pseudohalides like thiocyanate and cyanate in copper(II) complexes of 2-benzoylpyridine semicarbazone: Monomer, dimer and polymer

Synthesis, Spectroscopy and X-ray Crystallography Structure of Pyridine 4-Carbaldehyde Semicarbazone Schiff Base Ligand

“…The selected bond distances and angles of HL are summarized at Table 2. The C=N bond length of HL is 1.285 Å which is in good consistent with the C=N bond distances in similar ligands [20][21][22][23][24][25][26][27][28][29]. Although the HL contains an aromatic cycle, there is no π-π stacking interaction in its structure.…”

“…Most of the semicarbazone ligands display keto-enol tautomerism in coordination to metal ion centers as neutral or deprotonated ligands [16][17][18][19][20]. Preparation of the pyridine 4carbaldehyde semicarbazone ligand (HL) was revealed by infrared spectroscopy (Figure 1).…”

“…The semicarbazones and thiosemicarbazones usually behave as chelating ligands, which are versatile in both neutral and anionic forms [16][17][18]. Metal complexes of semicarbazones and thiosemicarbazones have gained special attention due to their importance in medicine and biological system [19][20]. Furthermore, the metal complexes of semicarbazones have demonstrated antimicrobial [21,22], anticancer [23], and antiviral activities [24,25].…”

ONO‐Pincer‐Type Coumarin‐Based Copper(II) Metalates: Effect on Alzheimer's Disease Pathologies in Caenorhabditis elegans

“…On comparison, only the complex [Cu(H‐7MAC‐Sc)(NO 3 ) 2 ] (2) (1.88×10 6 M −1 ) has higher binding constant value than ethidium bromide. These binding constant values are compared to the values in literature: Cu(II) complexes of 3‐carbaldehydechromone thiosemicarbazone (6.6×10 5 M −1 ), [27] 2‐benzoylpyridine semicarbazone [(1.9–6.0)×10 5 M −1 ], [28] 7‐hydroxy‐4‐oxo‐4[ H ]‐chromene Schiff bases (10×10 5 M −1 ), [29] and 6‐hydroxy‐3‐carbaldehyde chromone Schiff base (6.0×10 5 M −1 ) [30] . The obtained values are found to be higher than for Cu(II) complexes of 3‐carbaldehydechromone thiosemicarbazones (6.6×10 5 M −1 ), suggested the intercalative binding of the complexes with DNA which was further confirmed by EB displacement studies.…”

Molecular Switching of Copper Complexes with Quaterpyridine

“…On the other hand, copper(II) prefers trigonal‐bipyramidal, square‐pyramidal, and octahedral geometries, although appropriately designed ligands such as terpyridine‐based macrocycles can enforce copper(II) to adopt a pentagonal‐bipyramidal geometry. This extensive coordination chemistry of copper(I/II) implies a wide spectrum of supramolecular architectures such as grids, helicates, rack‐like complexes, or coordination polymers . It needs to be highlighted that the octahedral geometry of copper(II) complexes is severely distorted, which is associated with the Jahn–Teller effect (JTE) …”